I saw a guitarist throw a tantrum on stage one time because I suppose things weren't going his way. He just stopped playing in the middle of a song and a set. The other band members looked extremely embarassed by the incident and iirc they left the stage. I've seen other bands beat horrible odds (stolen eqt-playing with rented amps/guitars/drums and broken strings in the middle of songs) and never missed a beat. "The Show Must Go On" is a main criteria imho of proffesionalism in any music/ stage performers.
http://bandmix.com/zxyz/
http://www.myspace.com/zxyz1
http://www.myspace.com/zxyz1